1) Field of the Invention
The present invention relates to a printing head incorporated in a wire-dot printer, and more particularly, to improvements of such a wire-dot printing head.
2) Description of the Related Art
As is well known, a wire-dot printer represents an impact printer, and such printers are in wide spread use as office-type printers because the running costs thereof are relatively low. Nevertheless, the wire-dot printer is inherently noisy, and produces considerable vibration during the operation thereof, and this constitutes a factor in hindering the spread of the wire-dot printer as a personal-use type.
Japanese Unexamined Patent Publication (KOKAI) No. 4(1992)-70356 discloses a wire-dot printing head, the interior of which is partially charged with gel-like silicone resin for damping the noise and vibration produced during the operation thereof. The gel-like silicone resin is obtained from silicone oil, by hydrosilylation reaction, and has a crosslink density 1/5 to 1/10 less than that of silicone elastomer. The gel-like silicone resin can exhibit a desired viscoelastic property (elastic coefficient, dissipation factor) to effectively damp the noise and vibration produced by the operation of the printing head. Nevertheless, the inertial mass of the printing head is increased due to the charging of the gel-like silicone resin, to thereby cause an amplification of lateral shaking of a wire-dot printer in which this type of printing head is incorporated, and this lateral shaking of the printer produces another noise. Further, the increase in the inertial mass of the printing head impedes the high-speed printing operation of the printer, because it is difficult to quickly accelerate and decelerate the printing head since having an increased inertial mass.